How do I achieve an accelerando using MIDI in Cubase 9 ?
(Same for accelerato, rallentando and ritardando)
Just play what you need then tempo map it.
Hippo
Do you mean just add a tempo track and adjust as desired?
If so, I’ve tried that but when it’s loaded into the destination project, there’s no tempo mapping on the midi. I can only seem to get the midi to load with tempo by allowing it to create a new project, but that’s not what I need.
I need the exported midi to be import-able with tempo changes (if that’s the only way to do this with MIDI for accelerando etc) in Cubase and different DAWs.
If your exporting as a standard midi file the midi spec from memory only allows on the fly tempo messages in the first track which is used as a the control track in Type-1 midi files.
Type 0 only allows a fixed tempo as far as I can remember in the header.
Its been over 20 years since I’ve done in depth midi stuff and someone here may know more.
Hippo
You can do this in the Tempo Track Editor. Project > Tempo Track or press Ctrl+T. It works similar to editing CC controller data.
Yes, that’s what I have been doing but it’s not importing the tempo in the other project.
Check Preferences/ Midi file/ Ignore Master Track on merge is NOT checked
Hippo
Thanks, that sorted that one 
I do now need to figure out how to get the accelerando to work in the Score Editor. It applies it in the score editor but it does not play back the accelerando.